ts-data-forge/dist/functional/optional/impl/optional-is-none.mjs

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import { NoneTypeTagName } from './tag.mjs';

/**
 * Checks if an {@link Optional} is {@link None}. Acts as a type guard.
 *
 * @example
 *
 * ```ts
 * const optionalValue = Optional.none as Optional<number>;
 *
 * if (Optional.isNone(optionalValue)) {
 *   // Type narrowed to None
 *   assert.isTrue(true); // optionalValue is None
 * }
 * ```
 *
 * @template O The {@link UnknownOptional} type to check.
 * @param optional The {@link Optional} to check.
 * @returns `true` if the {@link Optional} is {@link None}, `false`
 *   otherwise.
 */
const isNone = (optional) => optional.$$tag === NoneTypeTagName;

export { isNone };
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